Self-contained and self-propelled machine for heat fusing polyolefin pipes

ABSTRACT

Polyolefin pipes are welded end-to-end by a self-propelled, self-contained machine which performs all steps necessary to the process without need for any other machines or equipment. Hydraulically driven parallel tracks are independently controlled for maximum maneuverability. An hydraulically driven, computer controlled, reversible jaw assembly reciprocates the new pipe section relative to the exiting pipe line. A facer for trimming and squaring the pipe ends to be joined and a heater for melting the pipe ends for fusing are umbilically connected to the machine for on-board or remote operation. The computer, also on an umbilical, enables the operator to operate the machine in a normal mode in which the operator manually controls the facing, soaking and fusing processes or an automatic mode in which the fusing process is automatically controlled by the computer. The computer also allows the operator to choose a data logging mode in which the operating pressure, heater temperature and time data are recorded to provide a history for each joint made by the machine.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.08/934,305, SELF-CONTAINED AND SELF-PROPELLED MACHINE AND METHOD FORHEAT FUSING POLYOLEFIN PIPES, filed Sep. 19, 1997 now U.S. Pat. No.5,814,182.

BACKGROUND OF THE INVENTION

This invention relates generally to portable machines for fusingpolyolefin pipe and more particularly concerns a self-contained andself-propelled machine and method for the end-to-end treatment of twoaxially aligned pipe ends for the purpose of heat fusing such pipestogether.

The principle of heat fusion is to heat two surfaces to a designatedtemperature and then fuse them together by application of force. Thepressure causes flow of the melted materials, which causes mixing andthus fusion. When the polyolefin pipe is heated, the molecular structureis transformed from a crystalline state into an amorphous condition.When fusion pressure is applied, the molecules from each pipe end mix.As the joint cools, the molecules return to their crystalline form, theoriginal interfaces are gone, and the two pipes have become onehomogeneous pipe. The joint area becomes stronger than the pipe itselfin both tensile and pressure conditions.

The principle operations of this fusion process include clamping thepipe pieces axially to allow all subsequent operations to take place,facing the pipe ends to establish clean parallel mating surfacesperpendicular to the centerline of the pipes, aligning the pipe endswith each other to minimize mismatch or high-low of the pipe walls,heating at a first specified force in a melt pattern that penetratesinto the pipe around both pipe ends, joining the melt patterns with asecond specified force which must be constant around the interface areaand holding the molten joint immobile with a third specified force untiladequately cooled.

Presently known portable pipe fusion machines are typically four wheeledcart type machines such as described in U.S. Pat. No. 3,729,360; U.S.Pat. No. 4,352,708 and U.S. Pat. No. 5,013,376. While these machinesperform quite well, they require a good deal of labor and additionalexpensive equipment such as cranes, forklifts, tractors, trucks and thelike to load, unload and precisely position the machine on the pipeline.Many machines are damaged during the loading and unloading process.Furthermore, the operators experience stress and fatigue in maneuveringthe machines over difficult terrain and conditions.

In addition to the mobility, maneuverability and stability problems ofthe overall machines, various known machine components also presentadditional problems. The hydraulic systems are complex and unwieldy andrequire expenditure of considerable time and labor in preparation foroff-cart use. The hydraulics are limited in that they permit selectionof only a few operating pressures. The facing operation is complicatedbecause the facer is not easily maneuverable into and out of positionbetween the pipes by one operator when working with the machineoff-cart. The facer guide bearings, which are traditionally integral tothe body, wear and eventually accuracy in axial registration of thefixed and moving pipes is diminished. This results in undesirable downtime of the machine during repair and costly repair to the facer. Thejaw assembly necessary to grip and move the pipes during the processrequires the front of the cart to be at the free pipe end of the pipeline. The heater is awkward to store for transport and to support onsite during periods of non-use.

It is, therefore, an object of this invention to provide a machine, anda method using the machine, for fusing polyolefin pipes which are fullyself-contained. Another object of this invention to provide a machine,and a method using the machine, for fusing polyolefin pipes whichrequires no additional equipment to support operation of the machine.Still another object of this invention to provide a machine, and amethod using the machine, for fusing polyolefin pipes which hastransport tracks aligned for movement along an axis parallel to theaxial pipe alignment within the machine jaws. It is also an object ofthis invention to provide a machine, and a method using the machine, forfusing polyolefin pipes which is fully self-propelled for forward orreverse movement, left or right movement and pivotal movement about itscenter. A further object of this invention to provide a machine, and amethod using the machine, for fusing polyolefin pipes which is movablealong the pipeline from a completed joint to the next joint location.Another object of this invention is to provide a machine, and a methodusing the machine, for fusing polyolefin pipes which has a trackedundercarriage to increase mobility, stability and maneuverability. Yetanother object of this invention is to provide a machine, and a methodusing the machine, for fusing polyolefin pipes which is easilymaneuverable over difficult terrain. It is also an object of thisinvention to provide a machine, and a method using the machine, forfusing polyolefin pipes which facilitates axial alignment of the machinewith the pipeline. A further object of this invention is to provide amachine, and a method using the machine, for fusing polyolefin pipeswhich has a low center of mass to increase stability. Another object ofthis invention is to provide a machine, and a method using the machine,for fusing polyolefin pipes which has a jaw assembly easily removed fromthe machine into remote or in-ditch positions. Yet another object ofthis invention is to provide a machine, and a method using the machine,for fusing polyolefin pipes which is computer controlled for operationin a variety of modes. Another object of this invention is to provide amachine, and a method using the machine, for fusing polyolefin pipeswhich is computerized to permit selection of a wide range of operatingpressures. Still another object of this invention is to provide amachine, and a method using the machine, for fusing polyolefin pipeswhich having a facer with wear compensating guide bearings which areeasily replaceable in the field.

SUMMARY OF THE INVENTION

In accordance with the invention, a machine and method are provided forend-to-end welding of polyolefin pipes. The machine is self-propelledand self-contained to perform all steps necessary to the welding processwithout need for any other machines or equipment. A chassis is supportedon a pair of independently rotatable parallel tracks so as to permitlineal motion of the chassis in forward or reverse direction, turningmotion of the chassis in left or right directions and rotational motionof the chassis about its center.

A jaw assembly mounted on one side of the chassis has a pair of fixedjaws for gripping an end of an existing pipe line and a pair of slidingjaws for gripping an end of free section of pipe to be welded to theexisting pipe line. The sliding jaws move in unison on a carriagemounted on parallel guide rods extending on diametrically opposite axesin a horizontal plane in relation to the longitudinal central axis ofthe pipe line. Preferably, the pipe line and guide rod axes are parallelto the longitudinal axes of the tracks. It is also preferred that thejaw assembly be mounted on a skid that can be secured to the chassis ineither a fixed jaw or sliding jaw forward position and that the jawclamps be reversible so that the operator can access the jaws withoutreaching over the jaw assembly or the machine regardless of the skidposition.

The tracks and the carriage are driven by a power system mounted on theother side of the chassis. Preferably, the power system includes adiesel engine which drives an hydraulic quad pump and a generator. A 12volt battery, an electrical control box including a microprocessor andsupporting electronic devices and a diesel fuel tank are also part ofthe power system. The tracks are hydraulically driven by two of the quadpump sections and are manually controlled by the operator at a firstcontrol station at the rear of the power system. The first controlstation includes separate track control valves and an operator'sinstrument panel.

The hydraulic system reservoir is located between the power system andthe jaw assembly system on the chassis. An operator pendant and ahydraulic valve system are mounted on the chassis at a second operator'sstation toward the rear of the jaw assembly side of the chassis. Thevalve system allows the operator to manually control the hydraulicoperation of the motor of a facer which is used to trim the pipe ends toparallel alignment for junction. It is preferred that the facer and thepipe lifts be driven by the same pump section as serves one of thetracks. The pendant allows the operator to electronically control thehydraulic pressure of the sliding carriage, control the operations ofthe sliding jaws between “apart ” and “together” conditions and monitorthe carriage pressure and the operation of a heater that is used to meltthe pipe ends for fusion throughout the welding process. The pendantincludes a microprocessor which preferably enables the operator tooperate the machine in a normal mode in which the operator manuallycontrols the facing, soaking and fusing processes or an automatic modein which the fusing process is automatically controlled by themicroprocessor. The pendant microprocessor also allows the operator tochoose a data logging mode in which the carriage pressure, heatertemperature and time data are recorded to provide a history for eachjoint made by the machine.

Pipe lifts are provided on the chassis forward and rearward of the jawassembly to facilitate adjustment of the pipe position in the machine byuse of the hydraulic system at the second operator's station.Preferably, the pendant microprocessor includes a calculation algorithmto enable the operator to easily determine the fusing pressure to beapplied to the pipe ends being joined. Furthermore, the pendantmicroprocessor, in cooperation with a rotary encoder and variouselectrical and hydraulic components, enables the operator to select atleast as many as six operating pressures to be applied to the jawassembly carriage.

The facer is preferably mounted on the machine by use of a removablepivot pin on a facer linkage mounted on the power system side of themachine. The linkage facilitates manual transfer of the facer from ahold position in which the linkage is closed to a use position in whichthe linkage is open and facer guide brackets are seated on the carriageguide rods with the facer centered on the pipe line axis. The heater isstored in a bag mounted on a frame. The frame is adapted for insertionbetween the fixed jaws with brackets riding on spacers connecting thefixed jaws during machine transport and for free standing during thewelding processes. Furthermore, the skid can be removed from the chassisand placed into the pipe ditch, if desired. The operator pendant, thefacer and the heater may be extended away from the machine by umbilicalsfor use with the jaw assembly in in-ditch or remote operations.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to thedrawings in which:

FIG. 1 is a perspective view of a preferred embodiment of the weldingmachine;

FIG. 2 is a side elevation view of the machine of FIG. 1;

FIG. 3 is a front elevation view of the machine of FIG. 1;

FIG. 4 is a top plan view of the machine of FIG. 1;

FIG. 5 is an assembly perspective view of the machine of FIG. 1;

FIG. 5A is a side elevational view of a preferred embodiment of thecarriage of the machine of FIG. 1;

FIG. 6 is a perspective view of the undercarriage and tracks of themachine of FIG. 1;

FIG. 7 is a perspective assembly view of a preferred embodiment of thereservoir of the machine of FIG. 1;

FIG. 8 is a bottom perspective view illustrating a preferred embodimentof the chassis of the machine of FIG. 1;

FIG. 9 is a side perspective view of the chassis of FIG. 8;

FIG. 10 is a top perspective view of the chassis of FIG. 8;

FIG. 11 is a left side perspective view of a preferred embodiment of thepower system of the machine of FIG. 1;

FIG. 12 is a right side perspective view of the power system of FIG. 11;

FIG. 13 is a rear perspective of the power system of FIG. 11;

FIG. 14 is a rear perspective of the power system of FIG. 11;

FIG. 15 is a perspective view of a preferred embodiment of the pivotmechanism of the machine of FIG. 1;

FIG. 16 is a front elevation illustrating the operation of the pivotmechanism of FIG. 15;

FIG. 17 is a front elevation illustrating the operation of the pivotmechanism of FIG. 15;

FIG. 18 front elevation illustrating the operation of the pivotmechanism of FIG. 15;

FIG. 18A is a perspective view of a preferred embodiment of the framefor supporting the heater of the machine of FIG. 1;

FIG. 19 is a schematic diagram illustrating a preferred embodiment ofthe hydraulic system of the machine of FIG. 1;

FIG. 20 is a schematic diagram illustrating the electrical system of themachine of FIG. 1;

FIG. 21 is a schematic diagram illustrating a preferred embodiment ofthe portion of the electrical system of the machine of FIG. 1;

FIG. 22 is a schematic diagram illustrating a preferred embodiment ofthe portion of the electrical system of the machine of FIG. 1;

FIG. 23 is a schematic diagram illustrating a preferred embodiment ofthe portion of the electrical system of the machine of FIG. 1;

FIG. 24 is a schematic diagram illustrating a preferred embodiment ofthe portion of the electrical system of the machine of FIG. 1;

FIG. 25 is a graphic representation of a typical display on the operatorpendant of the machine of FIG. 1;

FIG. 26 is a flow diagram illustrating the enabling and accessingprocedures for optional data logging and automatic modes of the machineof FIG. 1;

FIG. 27 is a graphic representation of a microprocessor calibrationarray for the machine of FIG. 1;

FIG. 28 is a flow diagram for the pressure calibration process for themachine of FIG. 1;

FIG. 29 is a flow diagram illustrating the automatic pressure controloperation of the microprocessor of the machine of FIG. 1;

FIG. 30 is a graphic demonstration of a display screen shown on theoperator pendant of the machine of FIG. 1 for diagnostic purposes;

FIG. 31 is a flow diagram illustrating the data logging process of themachine of FIG. 1;

FIG. 32 is a front end plot of a pressure profile during fusiongenerated in the data logging mode of the machine of FIG. 1;

FIG. 33 is a summary plot of a pressure profile during fusion generatedin the data logging mode of the machine of FIG. 1;

FIG. 34 is a flow diagram illustrating of the report upload process ofthe machine in FIG. 1 in the data logging and automatic modes;

FIG. 35 is a flow diagram illustrating of the report download process ofthe machine in FIG. 1 in the data logging and automatic modes;

FIG. 36 is a top plan view of a modified portion of the machine framefor use with a preferred embodiment of the jaw assembly skid;

FIG. 37 is a side elevation view of the modified portion of the machineframe shown in FIG. 36;

FIG. 38 is a top plan view of a preferred embodiment of the jaw assemblyskid;

FIG. 39 is a side elevation view of the skid of FIG. 38;

FIG. 40 is a rear elevation view of the skid of FIG. 38; and

FIG. 41 is a side elevation view illustrating first and second mountingpositions of the skid of FIGS. 38, 39 and 40 on the modified frame ofFIGS. 36 and 37.

While the invention will be described in connection with a preferredembodiments and methods of operation, it will be understood that it isnot intended to limit the invention to those embodiments or methods. Onthe contrary, it is intended to cover all alternatives, modificationsand equivalents as may be included within the spirit and scope of theinvention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION GENERAL ARRANGEMENT

A preferred embodiment of a fully self-contained and self-propelledwelding machine M for on-site alignment, facing, heating and fusion ofthe ends of two axially aligned polyolefin pipes is illustrated in FIGS.1 through 5. The welding machine M consists essentially of a machineframe or chassis C mounted on a track drive T and carrying a powersupply system P, a jaw assembly J, lift roller assemblies L andhydraulic and electric operating systems Y and E.

The power supply system P has an electrical generator and hydraulicpumps driven by a diesel engine to provide all power required for thetransportation and operation of the machine M. The jaw assembly J hasfixed and sliding pipe gripping jaws mounted on a skid which can bereversibly loaded on the machine M in forward or reverse alignment. Thejaw assembly J aligns the connected and free sections of pipe to bejoined and reciprocates the free section of pipe toward and away fromthe connected section of pipe or the welding process apparata that maybe inserted between the pipes. The pipe lift roller assemblies L haveV-seats at the front and rear of the chassis C which are hydraulicallyraised and lowered to maintain the connected and free sections of pipeat a desired level in relation to the machine M and the jaw assembly J.The hydraulic and electric operating systems Y and E consist of a totalpackage of components and connections including microprocessorsnecessary to allow an operator to control the operation of the powersupply system P and the jaw assembly J in the performance of theirvarious functions. A facing assembly F is preferably pivotally mountedon the machine M for insertion of its hydraulically driven facer betweenthe pipe ends to plane their surfaces into proper alignment for fusingto a good joint. A free standing heater H is connect able to thegenerator for power and is connect able to the electrical operatorsystem E for control and is insertable between the pipe ends to bejoined to heat them to a molten or fusible state. The operations of thefacer and the heater H are controlled by the hydraulic and electricsystems Y and E of the machine M.

TRACK DRIVE

The track drive T is illustrated in greater detail in FIG. 6 andincludes left and right tracks 11 and 13 mounted on track frames 15 and17 and driven by hydraulic wheel motors 19 and 21. Preferably, thetracks 11 and 13 are made of rubber and travel on roller sprockets andthe motors 19 and 21 include parking brakes and dynamic brakes. Anadjustable track tension mechanism is also desirable. The HINOWA modelPT15G track assembly with anti-cavitation valves, negative brakes andrubber tracks has been found to be quite suitable for the purpose. Thetrack frames 15 and 17 are secured in parallel alignment by anundercarriage assembly 23. Mounting brackets 25 and pads 27 are providedon the undercarriage assembly 23 for purposes hereinafter explained.

HYDRAULIC FLUID RESERVOIR

Looking at FIGS. 7 and 8, the hydraulic fluid reservoir 31 which servesthe hydraulic system of the machine M includes a fluid retaining basin33. Pads 37 are provided on the lower portion of the basin 33 to rest onthe undercarriage pads 27 to support the reservoir 31. Hose connections39 and a refill port 41 are provided in the reservoir 31. A controlmanifold 43 and an hydraulic system electrical junction box 44 aremounted at the rear of the reservoir 31 above the reservoir drain plug45.

CHASSIS

Looking at FIGS. 8-10, the chassis C consists of a tubular frameessentially arranged in rectangular sections extending in thelongitudinal direction of the machine M, the right hand rectangularsection 47 generally supporting the power supply system P of the machineM, the middle rectangular section 49 generally supported by thehydraulic reservoir 31 and the left hand rectangular section 51generally supporting the jaw assembly J of the machine M. As shown, therear of the right hand rectangular section 47 of the chassis C isdivided into forward and rear sections. The rear section includes theengine mounts 53. Two pairs of oppositely directed latching members 55and a pair of centrally located ears 57 with holes 59 are fixed to theleft hand rectangular section 51 for purposes hereinafter explained. Thepairs of latching members and ears 57 are transversely aligned inrelation to the longitudinal or travel direction of the machine M. Thechassis C also has a front bumper 61 along the front portion of itsright hand rectangular section 47. As seen in FIGS. 1-5 and 8-10, thechassis C also supports an operator pendant 63 which is pivotallyconnected in a pendant bracket 65 for 180 degree rotation from theoperable condition illustrated to a storage condition in which thependant 63 is shielded and protected by the walls of the bracket 65. Thependant 63 will generally be carried within the bracket 65 duringtransit of the machine M and is preferably maintained in the transitposition by a gas spring which will allow the pendant 63 to rotate intothe operating position shown.

PIPE LIFT ROLLER ASSEMBLIES

Continuing in FIGS. 1-5 and 8-10, the pipe lift roller assemblies L,which facilitate manipulation of the pipe sections to be welded to aproper elevation in relation to the machine M and the jaw assembly J,have longitudinal members 67 which are pivotally mounted to the chassisC by hinge pins 69. Vertical U-shaped plates 71 are welded to the freeends of the longitudinal members 67. A pair of rollers 73, preferablysections of pipe cut to a desired length and having nylon bearings 75 ontheir ends, are mounted in a V arrangement between ears 77 on each ofthe plates 71. As can best be seen in FIG. 3, shafts 79 extendingthrough the roller bearings 75 are connected at the bottom of each V bya pin 81 extending through apertures in flatted ends of the shafts 79.The level of each of the V aligned rollers 73 of the pipe lifts L isindependently changed by operation of an hydraulic cylinder 83 or 84which is pivotally pinned between the plate 71 and the undercarriagemounting bracket 25, as is best seen in FIGS. 2 and 8. An hydraulic pipelift valve assembly 85 is mounted on the chassis C adjacent the operatorpendant 63 for operator control of the cylinders 83 and 84.

POWER SUPPLY SYSTEM

The power supply system P is illustrated in greater detail in FIGS.11-14. A diesel engine 91 with an engine alternator 92 is served by afuel tank 93 and battery 95 which also provides power to the controlcircuits of the electric operating system E. A radiator 97 and an airfilter 99 are located behind the engine 91. An hydraulic pump 101 ismounted rearwardly of the radiator 97 in alignment with the engine crankshaft on an engine mount bracket 103. The hydraulic pump 101 shown is aquad pump having a manifold 105 connected between its third and fourthstages. Four hoses (not shown) extend from the reservoir connections 39to the pump 101. Left and right control valves 107 and 109 which operatethe left and right tracks 11 and 13, respectively, are mounted on therearmost portion of the power supply system P on an operator's station111 which includes the engine instrument panel (not shown). An exhaustpipe 113 extends from the engine 91 to a muffler 115. A generator 117 isaligned on the engine crank shaft in front of the bell housing 119. Anelectrical junction box 121 is mounted on the generator 117. A verticalplate 123, best seen in FIGS. 3-5, separates a main electrical controlbox 125 from the fuel tank 93. The front portion of the power supplysystem P is covered by a front shroud or hood 127 and the rear portionof the power supply system P is covered by a rear shroud or hood 129.

FACING ASSEMBLY

A pivot mechanism for the facing assembly F is mounted on the frontshroud or hood 127, as can best be seen in FIGS. 1-5, 11 and 12. Thepivot mechanism is shown in greater detail in FIG. 15. The pivotmechanism consists of a horizontal section of U-shaped channel 131 fixedon its side to the front hood 127 and extending parallel to thelongitudinal axis of the tracks 11 and 13 with the open side of thechannel 131 facing toward the left side of the machine M. A cam follower133 is slidably engaged for travel within the channel 131. A pair ofspaced apart vertical plates 135 and 137 are fixed to the front hood 127with a rod 139 fixed therebetween and aligned in parallel relationshipwith the channel 131. A sleeve 141 is mounted in sliding engagement onthe rod 139. A bracket 143 is fixed to the cam follower 33 and thesleeve 141 for forward and rearward motion parallel to the longitudinalaxis of the machine M. The bracket 143 consists essentially of a pair ofparallel plates 145 and 147 in a tilted T configuration with the base ofthe T mounted on the sleeve 141 and the lower end of the top of the Tfixed to the cam follower 133. A facer linkage is connected between theparallel plates 145 and 147. A tubular member 149 of the linkage ispivotally mounted at one end at the bottom of the T by a pin (not shown)which extends through the plates 145 and 147 and a sleeve 151 whichextends through the tubular member 149. An H-bar 153 is pivotallyconnected to the other end of the tubular member 149 by another pin (notshown) which extends through one end of the H-bar 153 with the free endof the tubular member 149 between the H bar uprights. The cross memberof the H-bar 153 is seated on the tubular member 149 when the linkage isin a closed condition. Thus, the tubular member 149 limits the downwardmotion of the H bar 153 in the linkage closed condition. Furthermore,the pin connecting the H bar 153 to the tubular member 149 is longerthan the distance between the plates 145 and 147, so that the pin canengage on the edge of the vertical portion of the T-shaped plates 145and 147. Thus, the downward motion of the tubular member 149 is limitedby the engagement of the pin with the bracket 143 when the linkage is inthe closed condition. Holes 157 are also provided in the free end of theH-bar 153 for insertion of a removable pin (not shown) to connect thefacer to the linkage, as will hereinafter be explained. A pair ofL-shaped detents 159 project upwardly from the bottom of the T on eachof the plates 145 and 147. A pin (not shown) that is inserted into theholes 157 through the H bar 153 to secure the facer to the linkage islonger than the distance between the detents 159 so that, when the faceris mounted on the linkage and the linkage is in its closed conditionsupporting the facer for transport, the detents 159 will engage with thepin (not shown) to prevent the linkage and the facer from rolling overshould the machine M traverse a hill so steep as to urge the facerlinkage. The free or upper end of the cross portion of the bracket 143is provided with a bumper 161 on which the facer will be seated when thelinkage is in the closed condition. This portion of the bracket 143 isalso provided with a latch 163 made of sheet metal with nylon rollers165 mounted on the upper portion of the latch 163 and aligned on an axisparallel to the longitudinal axis of the machine M for a purposehereafter explained. The operation of the pivot mechanism of the facingassembly F can best be understood in reference to FIGS. 16, 17 and 18.The facer 167 is seated in the pivot mechanism and its removablemounting pin (not shown) inserted through the H-bar 153 and its facer167 at the first pivot point 169. The linkage, shown in its closedcondition in FIG. 16, has its middle pin (not shown) resting on thebracket plates 145 and 147. The middle pin also provides a second pivotpoint 171. The cross member of the H-bar 153 is seated on top of thetubular member 149. The connection of the tubular member 149 to thebracket plates 145 and 147 provides the third pivot point 173 of thelinkage. In the closed condition of the linkage shown in FIG. 16, thefacer 167 is seated on the bumper 161 and is mounted for rotation aboutthe first pivot point 169. In this position, the rollers 65 of the latch163 ride above a top rest button 175 provided on the facer 167 toprevent the facer from tipping in a clockwise direction. The facer 167is provided with a first handle 177 which is positioned at approximately3 o'clock when looking at the facer 167 from the front. A second handle179 is located between approximately 10 and 11 o'clock on the facer 167.The second handle 179 is pivotally connected to the facer 167 about apin 181 and has a latching portion 183 at its free end which extendsaround and cooperates with a guide rod bracket 185 for reasons to behereinafter explained. An identical guide rod bracket 187 is alsoprovided on the facer 167 at a point diametrically opposite the firstbracket 185. As shown, the guide rod brackets 185 and 187 aresubstantially one-half octagons in cross section and are mounted bybolts (not shown) in conforming seats provided in the facer 167. Thefirst bracket 183 is aligned with its opening transverse to the facerdiameter and on its clockwise side when viewing the facer 167 from thefront of the machine M. The second bracket 187 has its opening alignedwith the facer diameter with the opening away from the facer 167. To usethe facer 167, it is necessary to transfer it to a position in which itscenter axis 189 is in alignment with the center axis 191 of the jawassembly J of the machine M. Looking at FIGS. 16 and 17, the movement ofthe facer 167 from the linkage-closed position to an intermediateposition is illustrated. As shown, the operator O grasps the firsthandle 177 of the facer 167 and pulls the facer 167 toward the operatorO. Initially, the first pivot point 169 will be moved along an arcuatepath to a point 193 during which motion the second pivot point 171 willhave rotated from approximately a 9 o'clock position to a 12 o'clockposition 195. The downward motion of the facer 167 in moving to theintermediate position shown in FIG. 17 is limited by the engagement ofthe second guide rod bracket 187 on one of the guide rods 197 of the jawassembly J. In this position, the first handle 177 of the facer 167 willhave moved to approximately between 4 and 5 o'clock and the upper handle179 will have shifted to approximately 12 o'clock. The operator O thenreleases the first handle 177 and grasps the second handle 179,continuing to pull the facer 167 toward the operator O to continue themovement of the facer 167 into its use or linkage-opened position, as isshown in FIG. 18. As this motion continues, the first pivot point 169 ofthe linkage moves arcuately from the intermediate point 193 on its pathto the final point 199 on its path. During this motion, the second pivotpoint 171 of the linkage will move substantially horizontally from itsintermediate position 195 to its final position 201. During the motionof the linkage from the intermediate to the final position, the secondguide rod bracket 187 on the facer 167 remains engaged with the Jassembly guide rod 197 until the first bracket 185 on the facer 167engages with a second guide rod 203 which is diametrically opposite andparallel to the first guide rod 197. While the guide rod brackets 183and 185 are semi-octagonal in configuration, they function as V-blockswith only two sides of each bracket 183 and 185 coming into contact withtheir respective guide rods 203 and 197. The two surface seating of thediametrically opposed guide rod brackets 185 and 187 on thediametrically opposed guide rods 203 and 197, respectively, biased bythe torque of the facer 167 during the facing process, assures theaccurate registration of the center axes 189 and 191 of the facer 167and the jaw assembly J, respectively. Since the guide rod brackets 185and 187 are replaceable, down time of the machine M resulting frommisalignment of the axes 189 and 191 of the facer 167 and the jawassembly J as a result of wear to the guide rod brackets 185 and 187 isminimized, replacement of each bracket 185 and 187 being possiblewithout detachment of the facer 167 from the linkage. In the operatingor linkage-open position, the latch 183 of the second handle 179 on thefacer 167 engages with the guide rod 203 to lock the facer 167 inposition with respect to the jaw assembly J. Preferably, the latch 183is spring loaded to hold it in its closed position on the guide rod 203.After use of the facer 167, the operation of the linkage to return thefacer 167 to its linkage-closed position is simply the reverse of theprocedure hereinbefore described. Looking back to FIG. 16, a thirdhandle 205 is located at approximately 8 to 9 o'clock on the facer 167to provide additional maneuverability for the operator O when the facer167 is used independently of the linkage. All that is necessary todisconnect the facer 167 from the linkage for independent use ortransport is to remove the pin at the first pivot point 169 between theH-bar 153 and the facer 167. The operation of the facer 167 in facingthe ends of the pipes is thoroughly explained in U.S. Pat. No. 3,729,360and that disclosure is herein incorporated by reference. The McElroyRotating Planar-Block facer with three cutter blades on a rotating blockchain driven by a hydraulic motor is suitable for the purposes of thisinvention.

JAW ASSEMBLY

Looking again at FIGS. 2-5 and 16-18, the configuration of the jawassembly J can be understood. A basic explanation of the structure andoperation of jaw assemblies for pipe welding machines is given in U.S.Pat. No. 3,729,360 entitled “Portable Thermoplastic Pipe FusionApparatus” and U.S. Pat. No. 4,352,708 entitled “Defined Force FusionMachine for Jointing Plastic Pipe.” The present jaw assembly J includesa front moving jaw 207 and a rear moving jaw 209 moved in unison by amoving jaw carriage 210, a front fixed jaw 211 and a rear fixed jaw 213.All of the jaws 207, 209, 211 and 213 are substantially identical. Askid 215 has a vertical yoke plate 217 fixed to and extending upwardlyfrom its front end. The front fixed jaw 211 is fixed to and extendsupwardly from the rear end of the skid 215. The guide rods 197 and 203are fixed between the yoke plate 217 and the front fixed jaw 211. Themoving jaws 207 and 209 are connected to form a carriage 210 mounted forreciprocating motion on the guide rods 203 and 197. As can best be seenin FIG. 4, the rear fixed jaw 213 is fixed to the front fixed jaw 211 byspacers 219 aligned with the guide rods 197 and 203 so as to beremovable from the jaw assembly J if the assembly J is used separatelyof the machine M. Removal of the rear fixed jaw 213 results in anassembly J that is much lighter and easier to handle and alsofacilitates the use of the assembly J to fuse a section of pipe to a Tjunction which makes gripping the pipe between two jaws impossible. Ascan best be seen in FIGS. 3 and 5, the upper and lower portions of eachof the jaws 207, 209, 211 and 213 are connected by a pivot pin 221 andon their opposite sides by eye bolts connected by pivot pins identicalin diameter. Thus, the direction of opening of each of the jaws 207,209, 211 and 213 can be reversed by pulling the pins 221 and invertingand repinning the upper portion of each of the jaws to the opposite sideof its lower portion. In addition, the front end of the skid 215includes a transverse member 223 engagable with the front or rearlatching members 55 on the chassis C shown in FIG. 8. Holes 225 are alsoprovided through the sidewalls of the skid 215 for alignment with theholes 59 through the ears 57 on the chassis C. Thus, the skid 215 isreadily reversible on the chassis C by removal of the locking pins (notshown) from the holes 59 and 225 in the ears 57 and the skid 215,disengagement of the skid 215 from one pair of latching members 55, 180degree rotation of the skid 215, re-engagement of the skid 215 with theopposite pair of latching members 55 and reinsertion of the locking pins(not shown) through the holes 59 and 225. Thus, the skid 215 can besupported on the frame or chassis C with the first or moving jaws 207and 209 forward of the second or fixed jaws 211 or 213 in a firstmounting position and with the second or fixed jaws 213 and 211 forwardof the first or moving jaws 209 and 207 in a second mounting position.Depending on the desired orientation of the skid 215 on the chassis C,the hinging of the upper portions of the jaws 207, 209, 211 and 213 canbe selected by use of the jaw pins 225 to assure that the operator O canaccess the jaw assembly J without reaching over the machine M. Themoving jaw carriage 210 is shown in greater detail in FIG. 5A. The guiderod 203 is fixed at one end 216 to the vertical yoke plate 217 and atthe other end 218 to the front fixed jaw 211. Bearings 212 and 214 slideon the guide rod 203. The bearings 212 and 214 are connected by acylinder 222 and are sealed to the guide rod 203 to define an hydraulicchamber 224 around the guide rod 203 which is divided by a piston 226.The hydraulic fluid source is connected to the chamber 224 on each sideof the piston 226 by ports 228 and 230. The other guide rod 197 supportsan identical arrangement. The moving jaw carriage 210 is hydraulicallyreciprocated on the guide rods 197 and 203 by the hydraulic system Y ina manner hereinafter described.

TRAPEZOIDAL SKID JAW ASSEMBLY

A specially preferred embodiment of the reversible jaw assembly isillustrated in FIGS. 36-41. Looking first at FIGS. 36 and 37, toaccommodate the preferred skid arrangement, the frame F of the machine Mshown in FIGS. 8-10 is modified to include a base 701 with upwardlyextending parallel sidewalls 703. The parallel sidewalls 703 supportspaced apart parallel rods 705 and 707 which are rigidly fixed to thesidewalls 703. In addition, the sidewalls 703 have two pairs ofapertures 709 and 711 which are oppositely aligned and symmetricallydisplaced between the rods 705 and 707. As shown, the central portion ofthe base 701 has a large opening 713, preferably substantiallysymmetrically located between the axes of the oppositely alignedapertures 709 and 711. The base 701 is reinforced by end cross members715 and 717 fixed to the base 701 and to the ends of the sidewalls 703.A rod 719 L-shaped at one end to form a handle 721 is slidablyinsertable through either pair of aligned apertures 709 or 711. Seats723 are fixed to one of the sidewalls 703 proximate each aligned pair ofapertures 709 and 711 so as to support the handle 721 of the rod 719inserted through the adjacent pair of apertures 709 or 711.

Turning to FIGS. 38-40, the preferred embodiment of the skid 731includes a pair of parallel spaced apart angle irons having one wall 733forming the base portion of the skid 731 and upright sidewalls 735. Thesidewalls are spaced apart by cross members 737 and 739 at a distancesuch that the sidewalls 735 may be snugly nestled between the sidewalls703 on the machine frame F. As shown, one of the cross members 737 isprovided with mounts 741 for connecting the jaw assembly hereinbeforedescribed to the skid 731. As can best be seen in FIG. 39, the sidewalls735 of the angle iron are cut at an angle so as to take on a trapezoidalconfiguration with the lower parallel side of the trapezoid being alongthe base 733 of the angle irons. The length of the angle irons is suchthat, when the skid 731 is nestled on the base 701, the center of theangled edges 743 and 745 will be substantially tangent to one pair ofaligned apertures 709 or 711 while the other angled edge 745 or 743 willbe substantially tangent to the more distant opposite rod 707 or 705fixed to the frame base sidewalls 703.

The reversibility of this preferred embodiment of the skid 731 is bestseen in reference to FIG. 41 which illustrates the modified base 701 ofthe machine M and the skid 731 disposed for mounting in forward 751 andreverse 753 positions on the base 701 of the machine M. As shown, in thefirst or forward position 751, one angular edge 743 of the skid 731 willbe tangent to the forward aperture 709 when the other angular edge 745of the skid 731 slides into tangential abutment against the rear fixedrod 707. Conversely, in the second or rearward position 753, the otherangular edge 745 of the skid 731 will be tangent to the rearwardaperture 711 when the one angular edge 743 of the skid 731 slides intotangential abutment against the forward fixed rod 705.

Thus, in operation of the trapezoidal skid jaw assembly, assuming theskid 731 is mounted in the forward position on the machine M, the handle721 on the rod 719 is rotated out of its seat 723 and withdrawn from theforward apertures 709 in the machine M. The skid 731 is then slid in aforward direction to clear the rod 707 at its rear. The skid 731 canthen be removed and rotated 180 degrees and again nestled in position onthe base 701. The skid is then slid forward until the edges 745 comeinto tangential abutment with the forward rod 715 on the machine frameF. The rod 719 is then inserted through the rearward apertures 711 inthe machine M. The edges 743 of the skid 731 should then besubstantially tangent to the rod 719. The handle 721 is then rotatedinto its seat 723 to lock the rod 719 in place. The pivot positions ofthe jaws of the jaw assembly are then reversed as hereinbefore describedto complete the transition.

HEATER

The heater H is shown in FIGS. 20 and 21 in block and schematic form.Typical heaters suitable for the purposes of this invention aredescribed in greater detail in U.S. Pat. No. 3,846,208 entitled“Combination Pipe Fusion Unit” and U.S. Pat. No. 4,227,067 entitled“Heater Adapter for Making Polyethylene Pipe Connections.” Looking atFIGS. 2 and 4, a frame 220 shown in FIG. 18A for supporting the heaterbag (not shown) in which the heater H is stored is insertable in thespace 227 between the front and rear fixed jaws 211 and 213 and issupported by the spacers 219 connecting the rear fixed jaw 213 to thefront fixed jaw 211. The frame 220 consists of a pair of horizontal bagsupports 229 integrally extending across a pair of parallel U-shapedbase members 234. The parallel base members 234 and bag supports 229 arespaced apart by a pair of side plates 236. A pair of legs 238 ofelongated W shape are pivotally connected to the plates 236 so as to beexpandable into a broader base area for increased stability of the frame220 on the ground. A pair of inverted U-brackets 242 are fixed to theplates 236 for seating on the spacers 219. The heater bag (not shown)has a collar into which the supports 229 are inserted as the bag isdropped into the frame 220 and the heater H rests on the top edge of theside plates 236.

HYDRAULIC SYSTEM

Turning to FIG. 19, the hydraulic system Y of the machine M isillustrated. Four lines 231, 233, 235 and 237 connect the left tracksection 239, the right track section 241, the high volume low pressurecarriage section 243 and the low volume high pressure carriage section245 of the quad gear pump 101, such as a CASAPPA PLP20,8-03S1-LOC/OC/20.8-LOC/OC/20.4-LOC/BA/10.1-LOB/BA-S+VEP/FC38GR.1-1, tothe reservoir 31. The left track section 239 of the pump 101 isconnected through a line 247 to the single spool monoblock valve withpower beyond 107, such as a WALVOIL SD5/1-P(KG3)/28L/AE valve, which isin turn connected across the left track hydraulic drive motor 19. Theright track section 241 of the pump 101 is connected by a line 251 tothe single spool monoblock valve with no power beyond 109, such as aWALVOIL SD5/1-P(KG3)/28L/AET valve, which is in turn connected acrossthe right track hydraulic drive motor 21. The valves 107 and 109 as wellas the drive motors 19 and 21 are connected by return lines to thereservoir 31 to complete the continuous flow of hydraulic fluid when theleft and right tracks 11 and 13 are being operated. The line 247extending to the left track valve 107 is serially connected to the threespool monoblock valve 85, such as a WALVOIL SD5/3-P(SV)/18L/416L/18L/AETvalve, which is in turn connected across the pipe lift cylinders 83 and84 at the front and rear of the chassis C and the facer motor 167. Thepipe lift valve 85 is also connected by a return line to the reservoir31 so as to complete the path of hydraulic fluid flow when the lefttrack 11 is not in use and the pipe lift cylinders 83 and 84 are beingoperated. The line 247 is also serially connected through the pipe liftvalve 85 to a first quick disconnect 257. A second quick disconnect 259is connected by a return line to the reservoir 31. The motor of thefacer 167 is insertable between the quick disconnects 257 and 259 andhydraulic fluid will flow through the motor of the facer 167 to thereturn 31 to maintain continuous flow of the hydraulic system when theleft track motor 19 and the pipe lifters 83 and 84 are not in use. Theleft and right track valves 107 and 109 permit the operator to chooseforward or reverse rotation of the tracks 11 and 13, respectively.Looking at FIGS. 1 and 19, the left spool 86 of the pipe lift valve 85controls the operation of the front pipe lift cylinder 83, the centerspool 87 controls the operation of the facer 167 and the right spool 88controls the operation of the rear pipe lift cylinder 84. As long as theengine 91 is running, hydraulic flow is continuous from the reservoir 31through the left track pump section 239, the left track valve 107, thepipe lift valves 86 and 88, the facer valve 87 and back to the reservoir31, as well as through the right track pump section 241 through theright track valve 109 and back to the reservoir 31. Pressure gauges 261and 263 are connected in the left and right track pump section lines 247and 251 for use in setting up the system for operation. The high volumelow pressure carriage section 243 of the pump 101 is connected by a line265 through a check valve 267 and another line 269 to the carriagecontrol manifold 43. The line 265 leading into the check valve 267 isalso connected to an unloading valve 273. The low volume high pressurecarriage section 245 of the pump 101 is also connected to the unloadingvalve 273 and to the input line 269 by a line 275. The unloading valve273 is thence connected by an outlet line 277 to a filter unit 279 andthence by a line 281 back to the reservoir 31. In the operation of thispart of the system Y, if the carriage 210 of the moving jaws 207 and 209is idle, the hydraulic system Y maintains a constant pressure on thecarriage control manifold 43. When the pump 101 comes up to pressure,the unloading valve 273 passes the high volume path oil back to thereservoir 31 through the filter 279. The low volume section 245 of thepump then maintains the pressure on the manifold 43 and seats the checkvalve 267. Looking at the carriage control manifold 43, a high pressurerelief valve 283 connects the input line 269 to the reservoir 31. Theinput line 269 also extends through a pressure reducing valve 285, suchas a Sun PVDB-LAN, to a pressure transducer 287, such as a SQD PTA6093.A servo valve 289, such as a FEMA 85820 PPC valve, is responsive to a DCcurrent derived from the pressure transducer 287 to meter the flow ofoil back to the reservoir 31 and controls the pressure reducing valve285 which controls the pressure applied to the carriage 210. Themanifold reduced pressure outlet line 286 is then connected to adirectional control valve 293 with a return to the reservoir 31. Adirectional control valve 293 is connected to quick disconnects 295 and296, to and from which the carriage cylinders 222 and 232 may be readilyconnected and disconnected by quick disconnect 297 for removal orreversal of the carriage jaw assembly J from or on the machine M.

ELECTRICAL SYSTEM

The electrical system E of the machine M is illustrated in block form inFIG. 20. The generator 117 is connected by a cable 301 to the generatorjunction box 121. From the junction box 121, another cable 303 extendsto one side of a connector 305. The other side of the connector 305 isconnected by a cable 307 to the heater H. The junction box 121 is alsoconnected by another cable 309 through a connector 311 to the mainelectrical control box 125. Three other connectors 313, 315 and 317 arealso mounted on the control box 125. One connector 313 connects a cable319 which extends to the engine 91 and the engine instrument panel atthe operator's station 111 for connection of a multitude of electricalcomponents which will be denoted hereinafter in the electrical schematicdiagrams of FIGS. 21-24 by the symbol a if they are on the engine 91 andby the symbol β if they are on the instrument panel at the operator'sstation 111. The control box 125 is connected through the other twoconnectors 315 and 317 by cables 321 and 323, respectively, to thehydraulics junction box 44. The hydraulics junction box 44 is in turnconnected by a cable 325 to the operator pendant 63. As seen in FIGS. 1and 20, externally, the operator pendant 63 has an emergency stop switch327, a key pad 329, two toggle switches 331 and 333, a rotary encoder335 and an LCD display 337. The operator pendant 63 is also adapted forconnection by a cable 339 to an external peripheral device such as aprinter (not shown). Internally, the operator pendant 63 houses avariety of electrical components which will be identified hereafter inthe electrical schematic diagrams of FIGS. 21-24 by the symbol y. Thehydraulic junction box 44 is also connected by four separate cables 341,343, 345 and 347 to the carriage pressure control valve 289, twocarriage control valve solenoids 288 and 290 and the carriage pressuretransducer 287, respectively. The internal components of the control box125 are identified hereafter in the electrical schematic diagrams ofFIGS. 21-24 by the symbol Δ.

The controls for the engine 91 are illustrated in the electricalschematic diagram of FIG. 21. The generator 117 is connected through aprotection device such as a breaker 353 and a normally open contact 354of a heater control relay 356 to the heater H and back to the generator117. The voltage across the generator 117 is indicated by a voltmeter355. The system battery 95 is preferably a 12 volt lead/acid battery.The starter motor 359 is connected across the battery 95 through anothernormally open starter solenoid relay contact 361. The starter solenoidrelay 357 is connected across the battery 95 through a four-way keyswitch 363 which has start, glow plug, off and run positions. The switchcontacts 365, 367 and 369 illustrate which switch contacts close in thestart, glow plug and run positions. When the key switch 363 is in thestart position, the circuit to the starter solenoid relay coil 357 isclosed and the contact 361 connecting the starter motor 359 closes. Theglow plug timer 371 is also connected across the battery 95 by the keyswitch 363 in the start position. The glow plug 373 is connected acrossthe battery 95 by the key switch 363 in the glow plug position and aglow lamp 375 indicates the status of the glow plug 373. An hour meter377 is connected across the battery 95 when the key switch 363 is closedin the start, run and glow plug positions. When the glow lamp 375 isout, the key switch 363 can be turned from the glow plug position to thestart position. The start, run and glow plug positions of the key switch363 also connect a control circuit relay coil 379, a throttle relay coil381, an oil pressure switch 383 and a water temperature switch 385across the battery 95. The control circuit relay coil 379 is protectedby a fuse 387. The operation of the throttle relay coil 381 iscontrolled by a throttle speed switch 389. The oil pressure switch 383and water temperature switch 385 are each series connected withindicating lights 391 and 393, respectively. The control circuit relaycoil 379, throttle relay coil 381, oil pressure switch 383 and watertemperature switch 385 are also connected across the battery 95 alongwith a voltage regulator 395 and alternator 397. A charge indicatorlight 399 connected between the regulator 395 and the battery returnline indicates when charging is taking place. The throttle speed switch389 is open for low speed operation and closed for high speed operation.An input terminal of a microprocessor 401 in the main electrical controlbox 125 detects the position of the throttle speed switch 389. Athrottle speed solenoid 403 having pull in and holding currents isconnected across the battery 95 by a contact 405 of the throttle relaycoil 381. A timer 407 connected across the battery 95 by a contact 409of the fuel shut-off relay 467 applies an approximately 40 amp pull incurrent and then an approximately 0.8 amp holding current to a fuel shutoff solenoid 411 connected across the timer 407. A fuse 413 protectsthis circuit. Thus, the engine 91 can be shut off by operation of thekey switch 363 to open the starter solenoid contact 409 or by theoperation of the fuel shut off solenoid 411 resulting in cutting off thefuel supply to the engine 91. The remainder of the control circuit isprotected by a fuse 415 and a contact 417 of the control circuit relaycoil 379 which are series connected to the positive terminal of thebattery 95 as well as by the surge suppressor 416 and the reversevoltage protection diode 418.

The hydraulic system controls are illustrated in FIG. 22. The FEMA PPCservo valve 289 is connected across the battery 95 through a currentcontrol device 419 located in the main electrical control box 125. Thedevice 419 is also connected to the control box microprocessor 401 whichprovides a control voltage to the device 419 indicative of the pressuredesired at the carriage 210, as is hereinafter explained. The output ofthe carriage pressure transducer 287 is compared with the voltagedesired to determine when the desired pressure is obtained. The voltageapplied to the current control device 419 by the microprocessor 401 isselected by use of the encoder 335 in the operator pendant 63 as willhereinafter be explained. A +/−12 volt dc-dc converter 423 converts 12volts to 24 volts to power the devices contained in the main electricalcontrol box 125. The converter 423 is connected to a plus 24 voltterminal and a ground terminal of the control box microprocessor 401 andalso through an LED 425 which indicates when power to the control boxmicroprocessor 401 is on. For reasons to be hereafter explained, thehydraulic control system Y may also include a linear transducer 427connected across the battery 95 and mounted on the jaw assembly carriage210 to measure the travel distance of the carriage 210 if the machine Mis operated in an automatic mode. A digital converter 429 counts thetransducer pulses to determine the relative position of the carriage 210on its travel path and provides a signal to the control boxmicroprocessor 401 usable to determine when to stop and start thecarriage 210 and how far the carriage 210 is to move. A +/−15 volt dc/dcconverter 431 is also connected across the battery 95 through aprotective fuse 433. The converter 431 powers a low pass filter 435which provides a signal derived from the output of the carriage pressuretransducer 287 which is connected across the battery 95 to a terminal ofthe control box microprocessor 401.

Continuing on to FIG. 23, an audio alert device 437 mounted in theoperator pendant 63 is connected between terminals in a microprocessor440 in the operator pendant 63 and to the positive side of the battery95. One terminal of the microprocessor 440 is also connected to thebattery return or ground. A 5 volt regulator 441 serving the back lightof the LCD 337 in the operator pendant 63 is also connected across thebattery 95. An RTD module 445 is connected across the battery 95 and toseveral contacts in the control box microprocessor 401 and the operatorpendant microprocessor 440. The module 445 senses the temperature in theheater H and provides signals to the microprocessors 401 and 440 as ishereafter explained. The return line of the battery 95 is also connectedto the rotary encoder 335 with the output terminal of the encoder 335being connected to the operator pendant microprocessor 440. The encoder335 is connected to the integrated circuit decoder chip 447. The decoderchip 447 has an output to a port of the operator pendant microprocessor440. It also has an output which extends through a flip-flop switch 449to another port of the operator pendant microprocessor 440. Finally, anoutput of the encoder 335 is connected with an output of the decoderchip 447 to another port of the operator pendant microprocessor 440. Theencoder 335 is toggled to select a desired carriage operating pressureat which the encoder 335 is to be set.

Looking now at FIG. 24, the control system E may also include a photosensor 453 connected across the battery 95 to determine whether theheater H, the facer 167 or any other object has been inserted into thepath of the carriage 210. The photo sensor 453 provides a signal to thecontrol box microprocessor 401 to indicate the presence of such anobject. The heater control relay 356 is connected between a port of thecontrol box microprocessor 401 and the positive side of the battery 95.A pair of relay coils 455 and 457 are connected between the positiveside of the battery 95 and a pair of ports at the control boxmicroprocessor 401. The contacts 459 and 461 connect carriage togetherand carriage apart solenoids 288 and 290, respectively, across thebattery 95. The right toggle switch 331 on the operator pendant 63 isconnected between the battery return line and two inputs to the operatorpendant microprocessor 440. When the toggle switch 331 is flipped to the“apart” position, the carriage apart relay coil 457 causes its contact461 to close and the carriage 210 will move for its full travel distanceor until the operator O moves the toggle switch 331 or themicroprocessor 440 automatically stops movement of the carriage 210.When the toggle switch 331 is in the “together” position, the carriagetogether coil 455 closes its contact 459 to cause the carriage 210 tomove in a closing direction, again until either the operator O or themicroprocessor 440 terminates motion. The left toggle switch 333 of theoperator pendant 63 is also connected between the battery return lineand inputs to the operator pendant microprocessor 440. The left toggleswitch 333 is the pressure select switch enabling the operator O tocontrol the pressure applied to the carriage 210 at various stages ofoperation of the machine M. The signal at the ports of the operatorpendant microprocessor 440 are delivered to the FEMA PPC valve 289 viathe control box microprocessor 401. Serial ports are also provided inthe operator pendant microprocessor 440 for program downloading orreport downloading via the cable 339 to the operator pendant 63.Finally, the emergency stop switch 327 connects the engine kill relaycoil 467 across the battery 95 and also connects ports on the operatorpendant microprocessor 440 and the control box microprocessor 401. Theengine kill relay 467 is energized when the key switch 363 is on.

SOFTWARE

The control system of the machine M includes three computer units. Alloperation and user interface controls reside in the main or operatorpendant microprocessor 440 which is preferably a Z-World BL 1600 with512K battery-backed SRAM and 512K EPROM. The control box microprocessor401, preferably a Z-world PK2120 with 32K battery-backed SRAM and 32KEPROM, is physically connected to input and outputs of the machine M. Itis responsible for reading inputs, including pressure transducer anddigital inputs, and writing digital and analog pressure control valveoutputs. The RTD module 445, preferably a Dataforth SCM9B-1412, isresponsible for acquiring heater temperature readings. These threecomputers 440, 401 and 445 are connected to a two-wire RS-485communications network. The operator pendant microprocessor 440 sendscommands in ASCII format and polls the control box microprocessor 401and the RTD module 445 via a half-duplex protocol.

The software of the machine M permits selection of any of threeoperational modes for the machine M including a semi-automatic mode, anautomatic mode and a data logging mode. Preferably, the latter modes areenabled only upon entry of an enabling password. Typically, the pipewelding process requires application of at least three differentpressures to the pipe. The first is the facing pressure P1 which thecarriage 210 must exert in holding the pipe ends against the facer 167to trim the pipe ends to be welded. The second is the soak pressure P2which the carriage 210 must exert in holding the faced pipe ends againstthe heater H to bring them to a molten condition. The third is the fusepressure P3 that must be exerted by the carriage 210 in holding themolten pipe ends together during the fusion process. In someapplications, it is also necessary to apply a unique heat pressure P4greater than the soak pressure P2 which the carriage 210 will exert onthe faced pipe ends at the initiation of the heat cycle and a coolpressure P5 less than the facing pressure P3 which the carriage 210 willexert on the faced pipes.

The control box microprocessor 401 and the operator pendantmicroprocessor 440 are operational whenever the key switch 363 is in theglow plug, start or run positions. In the semi-automatic mode, the LCD337 displays the screen 501 shown in FIG. 25 on the operator pendant LCD337. The screen 501 includes a timer status 502, a date 503, real timein hours, minutes and seconds 504, a pressure display definition prompt505, a pressure calculation prompt 506, a direct pressure set prompt507, a programmed pressure selection indicator 508, a label toggleswitch 509, a menu 510, the desired temperature 511 of the heater H, apressure adjustment knob or encoder dial lock indicator 512, a real timecarriage pressure monitor 513, a carriage control direction indicator514 and a heater temperature indicator 515. The timer 502 allows theoperator O to time all or a portion of the pipe fusing process and isreset by a single press of the “O” key on the keyboard 329. The pressuredisplay definition prompt 505 allows any of a number of pressures up tosix to be displayed for selection. The pressure calculation prompt 506permits calculation of the recommended fusion pressure, including dragpressure, and assignment of that pressure to any one of the sixdisplayed pressure selection positions 508. The direct pressure setprompt 507 allows the operator to enter or type in the desired pressureusing the keypad 329. The operator O can also change the carriagepressure by depressing the rotary encoder knob 335 to unlock the dialand then rotating the encoder dial. The pressure adjustment knob lockindicator 512 indicates by the symbol “X” that the pressure cannot bevaried. The symbol “X” is removed when the rotary encoder pressureadjustment knob 335 is depressed. The pressure selector toggle switch333 allows the operator to select among the preprogrammed pressures 508.The real time carriage pressure readout 513 constantly advises theoperator of the carriage pressure in real time. The desired heatertemperature 511 allows the operator O to key in the desired operatingtemperature of the heater H and commands the operator pendantmicroprocessor 440 to set and maintain that temperature through theheater temperature control components. The heater temperature readout515 allows the operator to observe the heater temperature in real time.The on screen pressure and temperature readouts 513 and 515 eliminatethe need for conventional pressure and temperature gauges. The carriagedirection indicator 514 enables the operator O to reverse the carriagecontrol direction by use of two key strokes, the position of the arrowindicating the status of the carriage direction. The label toggle switch509 provides visual indication as to the identity of the pressureselected. For example, P1 may be indicated as the “facing” pressure, P2as the “soak” pressure and P3 as the “fuse” pressure. The menu 510allows the operator O to access the other modes of operation of themachine M including the automatic mode and the data logging mode.

The flow diagram for enabling and accessing the optional data loggingand automatic modes is shown in FIG. 26. After the operator uses themenu 510 to “select-an-optional-mode” 516, the system “compares the userpassword in EEPROM to the factory password in EEPROM” 517. The systemthen inquires if this is the “valid password for this optional mode”518. If the answer to this inquiry is “YES”, the system “compares userconfirmation number in EEPROM to factory confirmation number in EEPROM”519. If the answer to the inquiry 518 is “NO”, then the system “promptsthe user for password” 525. If the user types in a “valid password forthis operational mode” 521, then the system “saves user entered passwordin EEPROM” 522 and “compares user confirmation number in EEPROM tofactory confirmation number in EEPROM” 519. Otherwise, the systemreturns to “user selects an optional mode” 516. After the system“compares user confirmation number in EEPROM to factory confirmationnumber in EEPROM” 519, the system inquires if this is the “validconfirmation number for this optional mode” 523. If the answer to thisinquiry is “YES”, the system “proceeds to selected optional mode” 524.If the answer to the inquiry 523 is “NO”, then the system “prompts theuser for confirmation number 525. If the user types in a “validconfirmation number for this operational mode” 526, then the system“saves user entered confirmation number in EEPROM” 527 and “proceeds tooptional mode” 524.

Thus, the owner of a machine M can enable and disable the optional datalogging and automatic modes by entering factory programmed passwordsinto the system. Each of these modes has its own unique password and notwo machines or modes would have similar passwords. The passwords cannotbe modified in the field as they are factory installed. The first timean optional data logging or automatic mode is selected from the mainmenu 510, the machine owner will be prompted for a password and aconfirmation number. If the correct password and confirmation number areentered, the optional mode will be enabled as explained above forsubsequent use without any re-entry of the password. Once so enabled,the optional mode for which the password has been entered cannot bedisabled by turning off the machine M. To disable an optional mode, themachine owner must enter the enabling password into the system. The samepassword is thus usable to enable and disable a machine M.

Each machine M has a unique pressure calibration table which ismaintained in battery backed SRAM for instant access. The calibrationtable contains digital to analog converter DAC voltages required toproduce desired pressure readings at the transducer 287. When a certainpressure is required at the carriage 210, the software looks up thecorresponding DAC voltage and sends it to the pressure control valve289. The calibration table contains two subtables, one for DAC voltagesused for stepping to a higher pressure than the current pressure leveland one for stepping to a lower pressure than the current pressurelevel. Calibration is accomplished by writing a DAC voltage and waitingfor a time interval to read the pressure transducer 287. The voltage isthen increased by a given increment and the process repeated until themaximum pressure or DAC voltage is obtained. During calibration, thesoftware attempts to find the most ideal DAC voltages that produce thepressure readings closest to their targets. The pressure increments willbe determined by the resolution of the digital to analog converter andthe accuracy of the pressure transducer 287. The DAC voltage incrementis chosen to produce a sufficient pressure transducer resolution for thesoftware to build the calibration table. Increments of 20 psi have beenfound to be suitable. The calibration subtables are represented by twoarrays and the number of array elements is equal to the maximum systempressure transducer reading divided by the pressure increments. Forexample, if the maximum system pressure is 2,000 psi and the pressureincrements are 20 psi, there will be 100 elements in each array. Duringcalibration, the software reads the pressure transducer 287 to determinethe array element at which the DAC value is to be saved. The index tothe array element is determined by dividing the pressure transducerreading by the pressure increment. A typical array is illustrated inFIG. 27. In the array illustrated and assuming 10 psi increments, at 500millivolts a range of pressures from 103 to 108 psi resulted, giving atable index of 10, while at 564 millivolts a range of pressures from 142to 145 psi was obtained, providing a table index of 14. The flow diagramfor pressure calibration is provided in FIG. 28. At “initialization”531, the DAC voltage equals zero volts. The system “writes the DACvoltage” 532 and “waits a given amount of time for hydraulic system tosettle” 533. The pressure transducer 287 is then “read” 534 and thesystem inquires as to whether “difference between target and previouslysaved pressure is greater than difference between target and currentlyread pressure” 535. If the answer is “NO”, then the DAC voltage is“increased” 536. If the answer to the inquiry is “YES”, then the DACvoltage is “saved and used for current pressure reading” 537 beforeproceeding to an “increase of the DAC voltage” 536. After “increasingthe DAC voltage” 536 the system inquires as to whether the “DAC voltageis at a maximum” 538. If the response to this inquiry is “YES”, this isthe “end of calibration”. If the answer to the inquiry is “NO”, then thesystem returns to the step of “writing the DAC voltage” 532.

The operator pendant microprocessor 440 continuously monitors thepressure adjustment knob of the encoder 335. If the operator O turns thepressure adjustment knob 335, the software reads its position andcomputes an offset into the calibration table to locate a DAC voltage.This voltage is written to the pressure control valve 289 and thereading of the pressure transducer 287 is displayed giving real timepressure readings to the operator O at the pressure monitor position 513on the display screen 501. The pressure adjustment knob 335 allows theoperator O to increase the pressure in small increments. However, theoperator O may key in a desired pressure for large changes. Thecalibration table also permits an on demand pressure setting featurewhich allows the operator O to recall a stored pressure settinginstantly.

During operation of a machine M from an hydraulic fluid temperature at acold start condition through increased fluid temperatures due to systemwarm up or other factors, the preset hydraulic pressure may change. Inorder to maintain constant pressure on the carriage 210, the operatorpendant microprocessor 440 monitors the pressure transducer 287 andmakes corrections at given intervals. The reading of the pressuretransducer 287 is compared to the target setting and as the differencein pressure warrants a correction, the microprocessor 440 makesincremental corrections of sufficient magnitude to prevent largepressure fluctuations that would contribute to oscillation. Thisautomatic pressure control operation of the microprocessor 440 isillustrated in the flow diagram of FIG. 29. The pressure transducer 287is “read” 541 and then inquiry is made as to whether the “pressure isequal to the target” 542. If the answer to this inquiry is “YES”, thesystem proceeds directly to the “end of pressure correction” 543. If theanswer to this inquiry is “NO”, the system next inquires as to whetherthe “pressure is greater than the minimum system pressure” 544. If theanswer to this inquiry is “NO”, the system again proceeds to the “end ofpressure correction” 543. If the answer to this inquiry is “YES”, thesystem proceeds to inquire as to whether the “pressure difference isless than 160 psi” 545. If the answer to this inquiry is “NO”, thesystem again proceeds to the “end of pressure correction” 543. If theanswer to this inquiry is “YES”, the system proceeds to inquire as towhether the “pressure is less than the target” 546. If the answer tothis inquiry is “NO”, the system proceeds to “decrease the pressure bysmall increment 547 and then proceeds to the “end of pressurecorrection” 543. If the answer to this inquiry is “YES”, the systemproceeds to “increase the pressure by small increment 548 and againproceeds to the “end of pressure correction” 543.

Referring again to FIG. 25, the operator pendant microprocessor 440allows the operator O to input six pressures either by dialing in thepressure using the pressure adjustment knob 335, by entering thepressure directly by using the keypad 329 or by using the calculator 506to compute a recommended pressure. Furthermore, the operator O mayassign the six pressures for different functions by putting them inorder at the programmed pressure selector display 508, for example inthe order necessary to face, heat, soak, fuse and cool in the weldingprocess. To access the desired pressure, the operator O simply shiftsthe pressure or left toggle switch 333 upwards or downwards to go fromone pressure setting to the next. Furthermore, the operator O can labeleach of these pressures by use of the toggle switch label display 509.The reversal of the carriage directional control switch 331 by use ofthe two key press operation of the carriage direction indicator 514,enables the operator O to use the operator pendant 63 on either side ofthe carriage without disorientation.

By entering the desired heater temperature at the desired heatertemperature display 511 by use of the keypad 329, the operator O allowsthe microprocessor 440 to set and maintain the correct heatertemperature. The operator pendant microprocessor 440 monitors the heatertemperature RTD 445 continuously and turns on the elements of the heaterH when the temperature falls below the set point and turns off theelements when the temperature rises above the set point.

Preferably, the operator pendant key pad 329 is multi-functional in thatall of the keys can be assigned for multiple functions under programcontrol depending on the context of the operation. For example, whilethe numeric keys are used to enter numbers in most cases, they may alsobe used to access menu items when a menu is presented to the operator O.

The operator O may use the calculator 506 to determine the heat, soak,fuse and cool pressures to use in the system operation. The calculatorwill compute the pressure if the operator O inputs data with respect topipe diameter and thickness, inter facial pressure and drag pressure.Use of the calculator of the microprocessor 440 for this purpose is moreaccurate than nomographic determination of these pressures.

Diagnostic information can be accessed at all times to monitor criteriaindicative of the internal status of the control system. Thus, if theoperator O suspects that a part of the machine control is not operatingproperly, the menu 510 will route access to the diagnostic information,a typical display of which is illustrated in FIG. 30. The display screen551 shown on the operator pendant LCD 337 indicates the date 552, time553 and machine number 554. It also indicates the milivoltage 555 at theFEMA PTC valve 289, the milivoltage 556 at the pressure transducer 287,the temperature 557 of the heater H, the position in inches anddirection of motion 558 of the carriage 210, whether the heater H is onor off 560, whether the engine 91 is in high speed mode which enablesthe heater H or in low speed mode which disables the heater H and, inthe automatic mode of the machine M, whether the heater H is in or outof place 562 on the carriage 210. The screen 551 also indicates whetherthere is communication 563 between the pendant microprocessor 440 andthe control box microprocessor 401, whether malfunctions 564 are inreception or in transmission whether the RTD 445 is convertingtemperature to a digital signal 565, whether the control boxmicroprocessor 401 is operational 566 and whether the emergency stopbutton 327 has been operated 567.

In addition to the above described functions, the data logging modeallows the operator to record machine and employee information, recordpipe material and size information, record interfacial pressures, dragpressure, and recommended fusion pressures, record heater temperature,log pressure profiles during fusion, view recorded data on screen afterfusion, view pressure profiles on screen after fusion, print recordeddata and pressure profiles to a printer and upload recorded data andpressure profiles to a personal computer for further analysis andarchive.

The data logging mode begins logging data as soon as the operator Opresses a designated log key. Although the operator pendantmicroprocessor 440 scans the pressure transducer 287 every 60milliseconds, it only saves data changes instead of recording every datapoint read at 60ms intervals. When the log key is pressed, the operatorpendant microprocessor 440 saves the joint information including pipesize, employee number, joint and job numbers, etc. to report memory. Itthen saves the first data record and initializes the second data record.Each record is made up of two elements. The first element is the timestamp, preferably at 100 millisecond resolution, and the second elementis the pressure reading in PSI. Every 100 milliseconds, the operatorpendant microprocessor 440 updates the time stamp of the second datarecord and checks the pressure reading. If the current pressure readingis different than the pressure recorded in the second data record, thenthird and fourth data records are created to record the change inpressure. This process is repeated until the operator terminates thedata logging, or the report memory is full or the maximum recording timeof 65,500 milliseconds is exceeded. The flow diagram of FIG. 31illustrates the data logging process. When the operator O presses thelog key, the microprocessor 440 “assigns new report memory space” 571.It then “copies the pipe and joint information to report memory” 572. Itthen “sets up first and second data records” 573 beginning at a timestamp of zero milliseconds. It then inquires as to whether “100milliseconds has passed” 574. If the answer to this inquiry is “NO”, itcontinues to inquire as to whether “100 milliseconds has passed” 574. Ifthe answer to this inquiry is “YES” it “reads the pressure transducer”575. It then inquires as to whether the “pressure has changed since itwas last saved” 576. If the answer to this inquiry is “YES”, it “createstwo new data records and saves new pressure reading” 577 and then“updates the time stamp for current data records” 578. If the answer tothe “pressure change since last saved” inquiry 576 is “NO”, it passesimmediately to the “update time stamp for current data record” 578.After each update 578, it returns to the “100 milliseconds passed”inquiry 574 for repetition of the process.

Typically, the data logging mode printout shows the followinginformation:  1. Date and Time:  2. Joint Number:  3. Job Number:  4.Employee No.:  5. Machine ID:  6. Machine Model:  7. Piston Area:  8.Pipe Material:  9. Pipe Size: Interfacial Pressures: 12. Heat: 13. Soak:14. Fuse: 15. Cool: Recommended Gauge Pressures: 18. Heat: 19. Soak: 20.Fuse: 21. Cool: Recorded Data: 24. Drag Pressure: 25. DataLogger Probe:26. External Probe:

Typically, the data logging mode report also includes two graphs of thepressure profile during fusion, illustrated in FIGS. 32 and 33. Thefront end plot of FIG. 32 expands the front end of the pressure profileto reveal the heat and soak profile in more detail than the summary plotof FIG. 33. The summary plot shows the entire pressure profile from thetime the operator O starts logging until the time the operator O stopslogging data. Looking at the summary plot of FIG. 33, when the operatorO presses the log key, the system reads the pressure P₀ at the time T₀and proceeds with the flow chart process of FIG. 31. The P₀-T₀ readingprovides an initial data point and every 100 milliseconds the systemextends the line from the P₀-T₀ data point until a pressure change isnoted at data point P₀-T₁. The system then begins two new data recordsbeginning at the data point P₁-T₁ and executes another straight lineplot until another pressure change occurs at a data point P₁-T₂. Thisprocess is continued throughout the operation of the system.

The automatic mode automates the fusion procedure and allows theoperator O to record machine and employee information, record pipematerial and size information, record recommended fusion parameters,record actual fusion parameters, view recorded data on screen afterfusion, print recorded data to printer and upload recorded data to apersonal computer for further analysis and archive. In the eventoperator intervention is required, the automatic mode prompts theoperator O with an audible buzzer 437 and displays the appropriatemessage on the screen 337. The automatic mode interacts with theoperator O with step-by-step instructions, and performs automatic pipefusion. The automatic mode begins by prompting the operator O to enterjoint information and select a pipe and enter its size. It then promptsthe operator O to prepare the pipe for fusion, which includes facing thepipe, cleaning the heater H and installing the heater H. After the pipeis prepared, the operator O presses a key to start the fusion process.The operator pendant microprocessor 440 starts the fusion process byclosing the carriage 210 to bring the two pipe ends against the heaterH. After the pipe ends contact the heater H, the microprocessor 440begins to count down from the programmed heat time under heat pressure.At the end of the heat cycle, the microprocessor 440 drops carriagepressure to drag pressure and locks the carriage to enter the soakcycle. Near the end of the soak cycle count down, the microprocessor 440sets a high carriage pressure with the carriage locked and prompts theoperator O to standby to remove the heater H. At the end of the soakcycle, the carriage opens automatically for heater removal. The operatorO must remove the heater H within a given amount of time. The carriagecloses to bring the melted pipe ends together. Once the pipe ends makecontact, the microprocessor 440 begins counting down for fuse cycle.Some jointing procedures call for a cool cycle with a lower interfacialpressure than the fuse cycle. At the end of the fusion, the operator Ois given an opportunity to view the joint report on the screen, andprint the joint report to an optional printer. After that, the operatorO may choose to fuse another joint using the same parameters, or selectanother pipe material.

The automatic mode printout typically shows the following information: 1. Date and Time:  2. Joint Status:  3. Machine ID:  4. Machine Model: 5. Employee No.:  6. Job Number:  7. Joint Number:  8. Pipe Material: 9. Pipe Size: Target Actual 12. Heater Temp.: 13. Heat Time: 14. HeatPressure: 15. Soak Time: 16. Soak Pressure: 17. Open/Close: 18. Fusetime 19. Fuse Pressure: 20. Cool time: 21. Cool Pressure: 22. DragPressure:

The target column shows the time and fusion pressures recommended by thepipe manufacturer. The actual column shows the actual time and pressuresused in the automatic fusion.

In the automatic mode, the pipe and fusion parameters are preprogrammed.In the field, the operator O selects from a list of preprogrammed pipematerials and pipe size, and the computer looks up the correspondingfusion parameters for the selected pipe. While the automatic mode comeswith a factory installed list of parameters, the owner of the machinemay replace the factory installed parameters by downloading customparameters via a PC serial port. The parameter download protocol issimilar to that for uploading reports to the PC as is hereinafterdescribed in relation to both the data logging and automatic modes.However, instead of the PC requesting data from the operator pendantmicroprocessor 440, the operator pendant microprocessor 440 requestsdata from the PC in the case of parameter downloading.

The data logging and automatic mode reports can be uploaded to an IBM PCcompatible computer for further analysis and archive. A companionprogram that runs on the PC can transfer data stored in thebattery-backed SRAM of the operator pendant microprocessor 440 to the PChard drive. The optional RS-232 serial cable 339 connects the serialport of the PC to the serial printer port of the operator pendantmicroprocessor 440. The data transfer is based on a polling protocol, inwhich the PC requests data from the operator pendant microprocessor 440.The microprocessor 440 responds by sending the requested data blocks tothe PC. To minimize data transmission error, the data blocks are markedwith a data block prefix and a checksum suffix. If the PC received adata block with the incorrect prefix or checksum, the PC will resubmitthe request for the same data block.

The report upload flow diagram is illustrated in FIG. 34. Themicroprocessor 440 “listens for request” 581 from the PC. It theninquires as to whether the request made is a “valid header request” 582.If the answer to this inquiry is “YES”, the microprocessor 440 then“sends the header block” 583 to the PC and “resumes listening for therequest” 581. If the answer to the “valid header request” 582 is “NO”,the microprocessor next inquires whether that is a “valid data blockrequest” 584. If the answer is “YES”, the microprocessor 440 “sends therequested data block” 585 to the PC and resumes “listening for requests”581. If the response to the inquiry is “NO”, the microprocessor 440inquires as to whether an “end of request message” 586 has beenreceived. If the response to this inquiry is “NO”, the system returns to“listen for request” 581. If the answer to this inquiry is “YES”, themicroprocessor 440 will “end data transfer” 587.

The report download flow diagram is illustrated in FIG. 35. In thisprocess, the operator pendant microprocessor 440 will first “request aheader” 591 from the PC. It then “listens for the response” 592, andinquires as to whether the response is a “valid header block” 593. Ifthe answer to this inquiry is “NO”, the system returns to “requestheaders” 591. If the answer to this inquiry is “YES”, the microprocessor440 will “process header information” 594. The microprocessor 440 willthen inquire as to whether it is “finished reading all data blocks” 595and if the answer to this inquiry is “YES”, it “sends an end of requestmessage” 596 to the PC. If the answer to this inquiry is “NO”, themicroprocessor 440 “requests the next data block” 597 and again “listensfor response” 598. The microprocessor 440 then inquires as to whetherthe information received from the PC is a “valid data block” 599. If theanswer to this inquiry is “NO”, the microprocessor 440 will “request thenext data block” 600 and “return to listen for response” 598. If theanswer to this inquiry is “YES”, the microprocessor 440 “processes andsaves the data” 601 and then returns to the “finish reading all datablocks” inquiry 595.

OPERATIONAL

The machine M, already calibrated by the manufacturer, is transported tothe pipeline site, preferably by a pickup truck or trailer. In thenormal mode of operation, the switch 353 is set to the glow plugposition 367 until the glow plug indicator light 375 goes off. Theswitch 363 is then turned to the start position 365 in which the engine91 is started. The operator O selects low throttle speed by flipping thethrottle speed switch 389 to the “open” condition. The hydraulic pump101 operates immediately upon starting of the engine 91. The operator Omaneuvers the machine M from the transport vehicle by use of the leftand right track control valves 107 and 109 at the operator's instrumentpanel 111. Once the machine is in position, the facer 167, which wastransported resting on the guide rods 197 and 203, is rotated on thelinkage to the linkage closed position illustrated in FIG. 16. Theheater frame 220 along with the heater H and bag are removed from theirtransport position on the jaw spacers 219 and set in a convenient groundcondition. The carriage skid 215 is aligned on the chassis C, ifnecessary, by removal of the pins through the skid ears 57,disengagement of the skid 215 from the latches 55, 180 degree rotationof the skid 215, reengagement of the skid 215 with the opposite latches55 and reinsertion of the pins in the skid ears 57. If the skid 215 isrotated, the jaw pins are removed and the upper portions of the jaws207, 209, 211 and 213 repinned for opposite hand rotation to thatpreviously selected. Sizing rings are mounted on the inside surface ofthe jaws 207, 209, 211 and 213 to reduce the jaw opening to a diametersuitable for the size of the pipes to be joined. The operator O thenuses the valves 86 and 88 of the pipe lift valve assembly 85 to positionthe roller assemblies L at an initially desired level. The operator Othen further utilizes the track control valves 107 and 109 to finallyposition the machine M in longitudinal alignment with the axes of thepipes to be joined. The pipe lift control valves 86 and 88 are thenfurther used if necessary to assist in manipulating the pipe to itsdesired level in the machine M. With the pipes extending at least oneinch inwardly of the fixed 207 and 209 and moving 211 and 213 jaws, thejaws 207, 209, 211 and 213 are locked to secure the pipes in properalignment. The throttle speed is then increased to high by closing thethrottle speed switch 389. In the high speed position, the circuit forthe heater H is closed and the heater H begins to warm up. The operatorO then selects the “facing”, “soaking” and “fusing” pressures. The“fusing” pressure can be determined by use of the calculation algorithmby entering appropriate pipe size, wall thickness and other manufactureinformation in response to prompts in the calculation loop of thesystem. When all necessary pressure, time and temperature selectionshave been made and the heater H reaches the desired fusion temperatureas is indicated at the display position 515 on the operator pendant LCDas illustrated in FIG. 25, the operator O and the machine M are ready toperform the fusion operation.

With the moving jaws 211 and 213 spaced apart from the fixed jaws 207and 209, the operator rotates the facer 167 to the linkage fully openedposition with the facer brackets 185 and 187 seated on the guide rods203 and 197. Facer operation is then initiated by use of the facercontrol valve 87. This is usually done at maximum speed but the operatorO may change the valve position if a lower speed is desired. Theoperator O then toggles the carriage control switch 331 to the“together” position, at facing pressure, to bring the pipes against thefacer 167. If the facer 167 is not turning freely to trim the pipeedges, the operator O may reduce the pressure applied by the carriage210. The operator O continues operation of the facer 167 to trim thepipe until the operator O is satisfied that the pipe ends have beensufficiently trimmed so as to lie in parallel planes. The operator Othen moves the carriage switch 331 to its “stop” position and moves thefacer valve 87 to its “stop” position to terminate the facing process.The carriage switch 331 is then moved to the “apart” position until themoving jaws 211 and 213 are sufficiently spaced apart from the fixedjaws 207 and 209 to remove the facer 167. The operator O then switchesthe carriage switch 331 to the stop position and removes the facer 167by rotating the facer 167 back to the linkage fully closed condition.The operator O then inspects the pipe to be assured that a clean andsatisfactory surface has been put on the ends of the pipes. The operatorO then moves the carriage switch 331 to the “together” position at thefusion pressure so as to abut the pipes and permit an alignment check toassure that there are no gaps between the pipes, that the pipes are notoff axis and the pipes will not slip. If the operator O is not satisfiedwith the mating of the pipes, the facing process will be repeated untila satisfactory result is achieved. When the result is satisfactory, theoperator O will place the carriage switch 331 in its “apart” position tospace the pipes apart sufficiently for insertion of the heater H. Theoperator O will then place the carriage switch 331 in its “stop”position and will check the heater temperature reading 515 on thedisplay of the operator pendant 63. If the heater H is at the propertemperature, the operator O will move the carriage switch 331 to the“together” position to bring the pipe ends into contact with the heaterH. The operator O will then select the “soak” pressure which may betypically, but not necessarily, selected as 30 psi or may be determinedas the minimal force necessary to move the carriage 210 with a pipeconnected in the moving jaws 211 and 213. Thus, the “soak” pressure isthe pressure at which the pipes will be maintained in contact with theheater H with minimal or zero force applied against the heater H. Whenthe zero force condition is achieved, the operator O will change theposition of the carriage switch 331 to “stop” in which both carriagesolenoids 288 and 290 are deenergized and the carriage pistons arelocked to maintain contact of the pipes with the heater H atsubstantially zero force. The operator O may then press the “0” key onthe pendant 63 to initiate operation of the timer 502 so as to time the“soaking” of the pipe ends. The operator O will generally be guided bythe elapsed time of the “soaking” process and also by observation of thebead formed on the perimeter of the pipes as the polyolefin melts. Whenthe soaking process is completed to the satisfaction of the operator O,the operator selects the “fusion” pressure which is generally thehighest pressure selected for operation of the carriage 210. Theoperator O then moves the carriage switch 331 to its “apart” position tomove the pipes away from the heater H. Operating the carriage 210 at the“fusion” pressure assures that the moving jaws 211 and 213 will bespaced apart as quickly as possible from the fixed jaws 207 and 209. Theoperator O then removes the heater H as quickly as possible from itsposition between the pipes and moves the carriage switch 331 to its“together” position at the fusion pressure to bring the pipe endstogether. The operator then restarts the timer 502 by using the “0” keyon the pendant 63. When the timer 502 indicates that the desired fusiontime has elapsed, the operator O moves the carriage switch 331 to its“stop” position, the jaws 207, 209, 211 and 213 are opened to unclampthe pipe and the pipe lifts L are operated to lift the pipe out of thejaws 207, 209, 211 and 213. With the pipe disengaged from the jaws 207,209, 211 and 213, the operator O then moves the carriage switch 331 tothe “apart” position at any desired pressure and the fusion process iscomplete.

In the automatic mode, the machine M is operated identically as in thenormal mode until the heater H has been inserted between the pipes. Atthis point, the operator O presses the key pad assigned to the “autorun” mode and the system will automatically select the soaking andfusing pressures and time for the pipe identified to the system. Thefusion process is then fully automatic. In this mode, the carriage audioalert 437 will sound whenever the carriage 210 is moving. When theheater H is removed from between the pipes, the sensor 453 causes thecarriage switch 331 to move to its “together” position and, if theheater H is not removed by the operator O in time to permit the pipes tocome together, the cycle will be automatically aborted. Furthermore, theoperator pendant microprocessor 440 continually monitors the pressureapplied to the carriage 210 and the temperature of the heater H and if,at any time during the process, they are not within the limits required,the microprocessor 440 will automatically abort the cycle. This is truewith respect to any condition that would cause an interruption in theproper execution of the cycle, including, for example, a loss of dieselfuel or a shifting or slippage of the pipes within the jaws. When thefusion cycle is complete, the operator O continues the process as in thenormal mode of operation.

In the data logging mode, when the heater H has been inserted betweenthe pipes, the operator O will press the keypad assigned to “startlogging”. The system will then begin logging the carriage pressure, theheater temperature and the time as hereinbefore explained for the fusionprocess. When the fusion process is completed, the operator O will pressthe keypad assigned to “stop logging” to terminate use of the datalogging mode.

Thus, it is apparent that there has been provided, in accordance withthe invention, a machine and method that fully satisfies the objects,aims and advantages set forth above. While the invention has beendescribed in conjunction with specific embodiments thereof, it isevident that many alternatives, modifications and variations will beapparent to those skilled in the art and in light of the foregoingdescription. Accordingly, it is intended to embrace all suchalternatives, modifications and variations as fall within the spirit ofthe appended claims.

What is claimed is:
 1. For use with a machine for end-to-end welding ofpolyolefin pipes, a pipe gripping assembly comprising: a skid; a firstjaw fixed to said skid for securing a first pipe in alignment with alongitudinal axis; a carriage slidably mounted on said skid forreciprocal movement along said longitudinal axis; a second jaw fixed tosaid carriage for securing a second pipe in longitudinal alignment withrespect to the first pipe; means on said skid cooperable with a frame ofthe machine for aligning and supporting said skid on the frame with saidfirst jaws forward of said second jaws in a first mounting position andwith said second jaws forward of said first jaws in a second mountingposition; means for securing said skid to the frame in a selected one ofsaid first and second mounting positions; and means for pivotallyengaging upper and lower portions of said first and second jaws at afirst point external of the pipe in a first jaw arrangement and at asecond point external of the pipe and diametrically opposite said firstpoint in a second jaw arrangement.
 2. For use with a machine forend-to-end welding of polyolefin pipes, the machine having a basemounted thereon with parallel side walls, two spaced-apart parallel rodsrigidly fixed to and between the side walls and two pairs ofspaced-apart, oppositely aligned apertures symmetrically displacedbetween the rods through the side walls, a pipe gripping assemblycomprising: a skid having parallel side walls nestlable on the baseparallel to and between the base side walls, said skid side walls beingtrapezoidal and of length such that angular ends of said skid side wallsare between and substantially tangent to one pair of oppositely alignedbase side wall apertures and one of the rods in a first mountingposition and between and substantially tangent to the other pair ofoppositely aligned base side wall apertures and the other of the rods ina second mounting position; a first jaw fixed to said skid for securinga first pipe in alignment with a longitudinal axis; a carriage slidablymounted on said skid for reciprocal movement along said longitudinalaxis; a second jaw fixed to said carriage for securing a second pipe inlongitudinal alignment with respect to the first pipe; a rod insertablethrough the one pair of oppositely aligned apertures for securing saidskid to the base in said first mounting position and through the otherpair of oppositely aligned apertures for securing said skid to the basein said second mounting position; and means for pivotally engaging upperand lower portions of said first and second jaws at a first pointexternal of the pipe in a first jaw arrangement and at a second pointexternal of the pipe and diametrically opposite said first point in asecond jaw arrangement.
 3. For use with a machine for end-to-end weldingof polyolefin pipes, a pipe gripping assembly comprising: a base mountedon the machine; parallel side walls extending upwardly from said base;two spaced-apart parallel rods rigidly fixed to and between the sidewalls; two pairs of spaced-apart, oppositely aligned aperturessymmetrically displaced between the rods through the side walls; a skidhaving parallel side walls nestlable on said base parallel to andbetween said base side walls, said skid side walls being trapezoidal andof length such that angular ends of said skid side walls are between andsubstantially tangent to one pair of said oppositely aligned base sidewall apertures and one of said rods in a first mounting position andbetween and substantially tangent to the other pair of said oppositelyaligned base side wall apertures and the other of said rods in a secondmounting position; a first jaw fixed to said skid for securing a firstpipe in alignment with a longitudinal axis; a carriage slidably mountedon said skid for reciprocal movement along said longitudinal axis; asecond jaw fixed to said carriage for securing a second pipe inlongitudinal alignment with respect to the first pipe; a rod insertablethrough said one pair of said oppositely aligned apertures for securingsaid skid to said base in said first mounting position and through theother pair of said oppositely aligned apertures for securing said skidto said base in said second mounting position; and means for pivotallyengaging upper and lower portions of said first and second jaws at afirst point external of the pipe in a first jaw arrangement and at asecond point external of the pipe and diametrically opposite said firstpoint in a second jaw arrangement.
 4. For use with a machine forend-to-end welding of polyolefin pipes, the machine having a basemounted thereon with parallel side walls, a pair of opposing aperturesthrough the side walls and two pairs of opposing latching membersrigidly fixed to the side walls and symmetrically displaced on oppositesides of the apertures, a pipe gripping assembly comprising: a skidhaving parallel side walls nestlable on the base parallel to and betweenthe base side walls, said skid side walls having opposing aperturescentered thereon and a cross-member rigidly fixed therebetween andspaced apart from said opposing skid wall apertures by a distance suchthat, when said skid apertures are aligned with the base apertures, saidcross-member engages with one of the pairs of latching members in afirst mounting position and with the other of the pairs of latchingmembers in a second mounting position; a first jaw fixed to said skidfor securing a first pipe in alignment with a longitudinal axis; acarriage slidably mounted on said skid for reciprocal movement alongsaid longitudinal axis; a second jaw fixed to said carriage for securinga second pipe in longitudinal alignment with respect to the first pipe;a pair of pins insertable into aligned skid and base apertures forsecuring said skid to the base in said first and second mountingpositions; and means for pivotally engaging upper and lower portions ofsaid first and second jaws at a first point external of the pipe in afirst jaw arrangement and at a second point external of the pipe anddiametrically opposite said first point in a second jaw arrangement. 5.For use with a machine for end-to-end welding of polyolefin pipes, apipe gripping assembly comprising: a base mounted on the machine;parallel side walls extending upwardly from said base; a pair ofopposing apertures through said side walls; two pairs of opposinglatching members rigidly fixed to said side walls and symmetricallydisplaced on opposite sides of said apertures; a skid having parallelside walls nestlable on said base parallel to and between said base sidewalls, said skid side walls having opposing apertures centered thereonand a cross-member rigidly fixed therebetween and spaced apart from saidopposing skid wall apertures by a distance such that, when said skidapertures are aligned with said base apertures, said cross-memberengages with one of said pairs of latching members in a first mountingposition and with the other of said pairs of latching members in asecond mounting position; a first jaw fixed to said skid for securing afirst pipe in alignment with a longitudinal axis; a carriage slidablymounted on said skid for reciprocal movement along said longitudinalaxis; a second jaw fixed to said carriage for securing a second pipe inlongitudinal alignment with respect to the first pipe; a pair of pinsinsertable into said aligned skid and base apertures for securing saidskid to said base in said first and second mounting positions; and meansfor pivotally engaging upper and lower portions of said first and secondjaws at a first point external of the pipe in a first jaw arrangementand at a second point external of the pipe and diametrically oppositesaid first point in a second jaw arrangement.